U.S. Bureau of Mines experts demonstrate dynamite explosions to miners during Safety Congress in Bruceton, Pennsylvania.

Explosion trials thrill miners at Bruceton, Pennsylvania during a 'safety congress' sponsored by the U.S. Bureau of Mines. A blast by dynamite witnin an Experimental Mine, US Bureau of Mines in Bruceton. Smoke rises from the dynamite explosion. The experts of the US Bureau of Mines demonstrate the dynamite and powder blasts to the miners. A man presses a detonator and lets off another dynamite explosion in a mine shaft to show the proper usage of explosives in loosening mineral riches. The dynamite explodes and smoke rises. Men stand very near the explosion area.